#include <iostream>
#include <string>
#include <stdio.h>

using namespace std;    

static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";

static const std::string str = "123456780";

static inline bool is_base64(const char c)
{
    return (isalnum(c) || (c == '+') || (c == '/'));
}

std::string base64_encode(const char * bytes_to_encode, unsigned int in_len)
{
    std::string ret;
    int i = 0;
    int j = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];
    
    while (in_len--)
    {
        char_array_3[i++] = *(bytes_to_encode++);
        if(i == 3)
        {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;
            
            for(i = 0; (i <4) ; i++)
            {
                ret += base64_chars[char_array_4[i]];
            }
            i = 0;
        }
    }
    
    if(i)
    {
        for(j = i; j < 3; j++)
        {
            char_array_3[j] = '\0';
        }
        
        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
        char_array_4[3] = char_array_3[2] & 0x3f;
        
        for(j = 0; (j < i + 1); j++)
        {
            ret += base64_chars[char_array_4[j]];
        }
        
        while((i++ < 3))
        {
            ret += '=';
        }
        
    }
    
    return ret;
}

std::string base64_decode(std::string const & encoded_string)
{
    int in_len = (int) encoded_string.size();
    int i = 0;
    int j = 0;
    int in_ = 0;
    unsigned char char_array_4[4], char_array_3[3];
    std::string ret;
    
    while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
        char_array_4[i++] = encoded_string[in_]; in_++;
        if (i ==4) {
            for (i = 0; i <4; i++)
                char_array_4[i] = base64_chars.find(char_array_4[i]);
            
            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
            printf("str3=%c\n", char_array_3[0]);
            printf("str3=%c\n", char_array_3[1]);
            printf("str3=%c\n", char_array_3[2]);
            for (i = 0; (i < 3); i++)
                ret += char_array_3[i];
            i = 0;
        }
    }
    
    if (i) {
        for (j = i; j <4; j++)
            char_array_4[j] = 0;
        
        for (j = 0; j <4; j++)
            char_array_4[j] = base64_chars.find(char_array_4[j]);
        
        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);  
        char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];  
        
        for (j = 0; (j < i - 1); j++) ret += char_array_3[j];  
    }  
    
    return ret;  
}

int main(void)
{
    std::cout << base64_encode(str.c_str(), 10) << std::endl;
    std::cout << base64_decode(base64_encode(str.c_str(), 10))<< std::endl;
    return 0;
}